Acute lymphoblastic leukemia (ALL) is the most common malignancy of childhood with and estimated 2000 new cases in the United States each year. With current therapy over half of these children will be cured of their disease and will be at risk for the late effects of their therapy. We propose a multi-faceted study of Second Malignant Neoplasms (SMN's) occurring after childhood ALL. The first phase of the study will identify all cases of SMN's occurring in children with ALL registered with the Childrens Cancer Study Group (CCSG) since 1972. The estimated risk of developing a SMN following childhood ALL will be calculated and patient characteristics of this group of patients described. Cohort analysis will be performed in an effort to identify patient characteristics present at the time of diagnosis of ALL that may be predictive of increased risk for the occurrence of SMN's. In the second phase of the study two case-control studies will be conducted. The first of these case-control studies will examine risk associated with patient characteristics at diagnosis and the specific effects of chemotherapies and radiation therapy on the occurrence of second malignant neoplasms. Information regarding age, sex, WBC count, morphology, and immunologic characteristic of the leukemic cells are maintained for all patients by the CCSG and will be made available to this study for analysis. Therapy records for cases and controls will be reviewed for analysis of the effects of specific chemotherapeutic agents and radiation therapy. The second case-control study will test the hypothesis that a population at risk for the development of SMN's can be described by the patients past medical history, family history, or exposures. Telephone interviews will be conducted for cases and controls and data obtained regarding multiple parameters including family cancer history, other significant family disease history, patental exposures and occupations, patients exposures, pre-natal and peri-natal events, and pre-existing patient illnesses. These data will then be analyzed in an effort to identify any parameters that may define an at risk population. The information gained from this study will contribute important information as modification are made to decrease the toxicity while preserving the efficacy of existing treatment protocols for childhood ALL. A case-controls study will also be undertaken in an effort to identify pre-natal and peri-natal risk factors for neuroblastoma, the most common malignancy in the first year of life. This study will utilize information coded on birth certificates and supplemental information forms for cases of neuroblastoma identified and born in Minnesota and matched controls. The results of this study can provide valuable insight into pre-natal and peri-natal influences of several pediatric neoplasms.